Insulated copper based cable is commonly used for automotive wiring. Copper has high conductivity, good corrosion resistance and adequate mechanical strength. However, copper and copper based metals are relatively expensive metals and are also heavy.
Interest is weight savings and cost savings in automotive electrical wiring applications have made aluminum based cables an attractive alternative to copper based wires. However, some wiring and electrical connectors may remain copper based. Thus, there may be a transition somewhere in the electrical circuit between an aluminum based portion of the circuit and a copper based portion of the circuit. Often this transition may occur at the terminal because the terminal may remain copper based for reasons of size and complexity of shape that can be more easily achieved with copper based materials over aluminum based materials. The connection of aluminum based cable to a copper based terminal can produce a galvanic corrosion of the aluminum, if an electrolyte, for example salt water, is present. The galvanic reaction corrodes the aluminum because the aluminum or aluminum alloy has a different galvanic potential than the copper or copper alloys of the terminals. “Copper based” as used in this document means pure copper, or a copper alloy where copper is the main metal in the alloy. Similarly, “aluminum based” as used in this document means pure aluminum or an aluminum alloy where aluminum is a main metal in the alloy.
Referring now to FIG. 1, significant corrosion is known to occur between dissimilar materials when an electrolyte such as salt water is present. A conventional copper based terminal 35 as shown in FIG. 1 has a pair of insulator wings 36 and a pair of core wings 38 with a notch 40 therebetween. A stranded aluminum based cable 12 may have its connected exposed strand ends 15 of lead 16 substantially corrode when it is attached to a terminal 35 made from a more noble metal such as pure copper, brass, or another copper alloy. A four day long salt fog test has been demonstrated to substantially corrode away almost the entire aluminum lead 16. The notch 40 allows greater access of the salt and other electrolytes to contact the exposed strands 15. The lead 16 when corroded completely away causes a break in the electrical connection between the cable 12 and the terminal 35.
What is needed is an improved corrosion resistant connection between a cable and its connected terminal. What is also needed is a connection between aluminum based cable and copper based terminals with improved corrosion resistance through an improved seal to seal the aluminum cable from an electrolyte while maintaining electrical contact with the terminal.